How to Clean Mildew from Exterior Painted Wood in 6 Steps

As a homeowner, your outside space can be a sanctuary to unwind or a place of gathering for family barbecues and game nights. If you have outdoor space and have furnished it with painted wood furniture or even have a patio or external siding made of wood, there will likely come a time that it needs to be cleaned. If you live in a damp or humid climate, wood furniture is a prime candidate for growing mildew and this should be cleaned promptly before it becomes a much larger problem with mold overgrowth.

You can clean mildew from exterior painted wood surfaces like patios, siding, and other wood furniture in a few simple steps. You will need a little time and patience to get the job done as pressure washers and abrasive scrubbers can chip and damage the paint. Follow these 6 steps for easy cleaning.

While it can be off-putting to find mildew on your exterior painted wood items, prompting the instinct to immediately scrub or pressure-wash it off, you should not panic. There are gentle and easy ways to clean mildew off of painted wood and prevent it from happening again in the future while simultaneously maintaining the paint and the wood.

It is important that the paint on the wood is durable, I have put together multiple lists of the best exterior paints, check out these posts:

What Happens to Exterior Painted Wood if Left Uncleaned?

If exterior painted wood is left uncleaned, you run the risk of incurring more structural damage to your home or furniture along with increased health hazards. The presence of mildew usually indicates the presence of moisture.

Allowing mildew to continue growing on your exterior painted wood surfaces greatly increases the chances of mold growth which can be a health risk to your respiratory system and harder to clean as mold is more invasive.

The continuous presence of moisture that allows mold and mildew to grow, if ignored can cause your exterior wood surfaces to rot, compromising structural integrity and will ultimately need replacing.

Why is it Important to Clean Exterior Painted Wood?

It is important to regularly clean exterior painted wood surfaces to keep them free from harmful mold and mildew growth. Regular cleaning also allows you to inspect the condition of your overall property which could indicate larger underlying issues such as the cause of moisture retention in some areas versus others.

For example, if your house has exterior painted wood siding but has become ridden with mold or mildew, you should check for gutter clogs that could cause water to overflow onto the siding or it may be time to trim any shrubs or bushes that grow against the siding, causing moisture retention.

Pay special attention to areas that retain moisture the longest after frost or rain such as those that are not easily reached by direct sunlight as that is where mold and mildew are likely to grow on exterior painted wood surfaces.

clean wood deck painted

What You Will Need to Clean Exterior Painted Wood

For slight mildew build-up on your exterior painted wood, a mild dish detergent or all-purpose cleaner should suffice. Use caution if you choose to clean exterior wood with bleach as it can penetrate the wood and compromise its grain structure and integrity in the long run.

To avoid damage to the wood while scrubbing, ensure that the scrub brush you choose has fine, soft bristles as opposed to coarse ones. Most often, scrub brushes that are compatible with cleaning cars and boats should work well however, you can also use non-abrasive scrubbing pads or microfiber cloths for small jobs.

You also need to ensure that the sprayer head on your garden hose has adjustable settings. Exterior painted wood should not be cleaned at a high-pressure setting to avoid chipping the paint and damaging the wood grain. Settings that can spray a gentle-diffused stream of water work well.

How to Clean Mildew from Exterior Painted Wood?

1. Clear Away the Surrounding Area to be Cleaned

If you are cleaning a painted wood patio, remove any furniture, potted plants, or toys to clean efficiently and so that the entire area is exposed to sunlight and air for quicker drying. If you are cleaning painted wood furniture or siding, ensure there is nothing around it that could be damaged in the process of cleaning.

2. Create Your Cleaning Solution

Fill your bucket with warm water add your cleaning solution of choice diluting it to the instructions on the label. For dish soap, you can add 2 ounces of dish soap for every 1 gallon of water.

3. Prime Your Cleaning Brush

Allow your cleaning brush to soak in the cleaning solution for a few minutes to saturate and soften it with the cleaning solution.

4. Start Cleaning

For heavily soiled exterior painted wood that may be caked in dust or mildew, wet that area with your water and cleaning solution mix and allow it to sit for a moment to lift the dirt.

You are ready to start gently scrubbing the area, completing one wood panel at a time. Ensure your scrubber stays saturated with the cleaning solution for even cleaning and less risk of abrasion to the painted wood.

5. Rinse with Hose on a Gentle Spray Setting

Once you have scrubbed the area with cleaning solution and are confident that the dirt and mildew have been lifted, you can then give it a final rinse with water from a hose on a gentle spray setting to avoid chipping the painted wood.

Be careful to prevent water from pooling around the foundation of your house as this could cause larger structural damage to your home.

6. Repeat Scrubbing and Rinsing if Necessary

If you rinse off the solution and find that some mildew or dirt is left on the painted wood surface, you can scrub it gently with the cleaning solution again and give it another rinse.

If you are cleaning exterior painted wood patios, siding, or larger pieces of wood furniture, wait until it is fully dry before placing any décor or potted plants on or near them as any moisture retention from failure to dry could cause further mildew growth or wood rot.

If you discover that mold or mildew has started to penetrate any of the exterior painted wood, you may need to replace that wood panel altogether as the surface has been compromised, and wetting it to clean could further promote mold growth and structural damage.

Final Thoughts

While it can be off-putting to discover mildew on your exterior painted wood surfaces, it is worth trying to clean it yourself. In these few simple steps, you should be able to restore your exterior painted wood surface without chipping or damaging the paint or wood itself.

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